Thanks in large part to both, the Mets’ offense has become a lifeless mess.

A getaway-day lineup that was minus three starters combined with two bungled defensive plays and more bullpen misery were obvious factors in an 8-1 loss to the streaking Cubs today at Wrigley Field.

But make no mistake: The Mets’ third loss in a row wouldn’t have been possible without the continuing misadventures of center fielder Carlos Beltran and first baseman Carlos Delgado.

The fourth and fifth hitters in the lineup were MIA again, combining to go 1-for-6 with a harmless single and no RBIs.

Beltran is hitting .215 in the cleanup spot on surgically repaired knees, and Delgado — who left the bases loaded again today — is at .208.

“We need the guys at the top of the order to get on base and the guys in the middle of the order to drive them in,” said dejected David Wright, who was 0-for-3 today and 0-for-6 with a strikeout in the series.

Because of Beltran, and particularly Delgado, Willie Randolph’s club has become one-dimensional on offense. If Wright isn’t hitting, which was the case the past two games, the Mets are virtually no threat to score.

Delgado expressed no concern about his slump — “I feel great at the plate, and I’m seeing the ball good,” he said — but worry was obvious in Wright’s face.

“We’re having way too many 1-2-3 innings and giving some at-bats away,” the All-Star third baseman said. “We’re just not putting any pressure on the defense.”

That was the case again today, and it was especially inexcusable coming against Cubs starter Ted Lilly. A junkball-throwing left hander, Lilly began the day 0-3 with a 9.60 ERA.

The Mets offered little resistance, mustering four hits in six innings against him. The agony was most acute in the fourth, when they loaded the bases with one out in a scoreless game but came away with nothing thanks to popouts by Delgado and fill-in second baseman Damion Easley.

The hot-hitting Cubs, who are off to their best start since 1975 at 14-6, put the game away in the bottom of the inning with three runs off Mets starter Nelson Figueroa.

The Brooklyn native (1-1) qualified for hard-luck status largely because of Delgado’s botched play in the fourth on a two-out grounder by Lilly to second base. Delgado for some reason took himself out of covering first base, allowing Lilly to reach as Figueroa arrived to the bag late.

Reed Johnson predictably followed with a two-run single to make it 3-0, giving the Cubs all the cushion they would need against a punchless Mets offense.

“You can’t run off the play like that,” said Randolph, who also was upset about a poor throwing decision by shortstop Jose Reyes in the eighth. “There were some lack-of-focus plays [on the part of the Mets]. Figueroa deserved better than that.”

Figueroa also deserved better from the Mets’ bullpen, which was a liability for the second day in a row. Joe Smith and Jorge Sosa were pounded for a combined five runs, the bulk of them on an eighth-inning grand slam by Ronny Cedeno.

It was the second grand slam Sosa has allowed this year, and the season is 19 games old.

“You can’t make mistakes like we did with the way the bullpen struggled in this series,” Randolph said. “You can’t give a team like that opportunities, because you end up paying for it, to say the least.”